The present invention relates to the cooling of metal slabs and other metal products and to a process and apparatus for converting the energy which is released in the cooling process into a useful form.
In a typical metal processing facility such as an iron and steel mill, intermediate products such as semi-finished steel in the form of slabs, billets, blooms, castings, and so forth, are produced as part of the overall production process. These products, as well as the finished products, are produced either by rolling, by casting, or from various heated operations. In whatever manner they are produced, they are usually allowed to cool to approximately room temperature prior to subsequent rolling operations, finishing operations, or shipping. The purpose of this cooling is to facilitate their surface inspection and conditioning as well as to facilitate their subsequent handling. This cooling is normally accomplished in such a manner that the thermal energy is lost.
An example of this waste of energy occurs in the cooling of steel slabs which leave the slabbing mill or the continuous caster. In cooling from an initial temperature of approximately 1800.degree. F. to room temperature, approximately 550,000 BTU is wasted per ton of steel.
It is possible to conserve the sensible heat of slabs by performing subsequent finishing operations without intermediate cooling. However, in this case hot scarfing must be employed to condition the surfaces of the slabs, and hot scarfing, by virtue of its consumption of natural gas and oxygen, and because it removes an excess of metal from the slabs, uses at least as much energy as it saves in the sensible heat of said slab. Thus there is no saving of energy in the use of hot scarfing.
In the United States, where the annual production of slabs is approximately 60 million tons, the loss of energy in the slabs amounts to 24.times.10.sup.12 BTU per year, equivalent to almost 4,000,000 barrels of oil. Similar calculations can be applied to other semi-finished products, castings, finished products and the like, both ferrous and non-ferrous.
A purpose of this invention is to convert to a useful form the energy which is released from the cooling of metal slabs and other metal products.
A further purpose of this invention is to produce steam from the energy which is released from the cooling of metal slabs and other metal products.
A further purpose of this invention is to produce steam from or to convert to another useful form the energy which is released from the cooling of metal slabs and other metal products and to do so in an essentially continuous manner.
A further purpose of this invention is to provide accelerated cooling of metal slabs and other metal products.